Resign, Appeal or Go on Sick

My employer has declined my application to return to work after mat. leave part time 2-3 days a week for 2 prescribed allowable reasons. They know I don't want to work 5 days a week especially 5 afternoons but have said they would re-consider my application if I can provide a 5 day a week presence in the office, albeit part time. I don't want to go down this route as I wouldn't gain any time with my child and would have a reduced salary for no gain. They won't entertain 5 mornings. Basically, it's their terms or nothing.

My legal advisor has said he feels I have a good case providing what I say is correct and can be proved; that my employers reason for refusal isn't justified. My employer states that their ground for refusal is that my returning part time would have a detrimental effect on their ability to meet customer demand - I am a Secretary, I don't work in R&D or Sales and don't directly contribute to the delivery of products to the end user. If I appeal the compensation award is capped to 8 x 280. I only have until Friday to decide if to appeal or not.

I have received enhanced maternity pay but have not been sent my employers response to my notification or signed statement of undertaking. The statement of undertaking is your agreement to return to work for one calendar months service or repay the difference. The difference may be waived in exceptional circumstances. As I say I haven't signed it but have received the pay.

I have severe PND and could really do without this. The truth is my employer made my job redundant last year - they haven't attempted to or replaced me since going on maternity leave. If I don't return I seriously doubt they would replace me at all.

Do I:
a) resign
b) appeal and fight for 2/3 days. Keep my options open for taking it further.
c) tell them I'm going to go back full time and then go on sick leave due to PND.

I have 19 days accrued holiday owed to me and wondered whether I did resign whether they would waive the difference between enhanced and stat maternity if I said for them not to pay the holidays.
d) Or resign but tell them I have PND and am prevented from returning on medical grounds. AND still get the holiday pay.

My legal advisor has pointed out that my employer could POSSIBLY (but he doubts it) terminate my employment on the basis of gross misconduct for potentially abusing my employers sickness benefit - 3 months at full pay. However, I see my GP every few weeks and take anti-depressants. I am not lying!!!!! They could write to my GP, they could make me attend a medical examination - I'd be fine with all of that.

Do I need the hassle though?

What are your thoughts? Quite upset about it all and feel really down at present.